1. Field of the Invention
This invention relates in general to fluid-actuated wellbore tools for setting in a wellbore, and in particular to tubing conveyed inflatable packers and bridge plugs which are set within a wellbore, then released from the tubing string by which they are conveyed, and later resecured to the tubing string for retrieval from the wellbore.
2(a). Background of the Invention
During operations for treating productive, hydrocarbon bearing earth formations to enhance production of oil and gas from wellbores, frequently well treatment tools, such as fracturing tools and wash tools, are utilized for pumping treatment fluids into these productive formations. Wash tools and fracturing tools typically have seal cups which are used for sealing a wellbore to direct treatment fluids into a productive formation. Often seal cups deteriorate and require replacement before efficient completion of formation treatment operations.
When seal cups require replacement, it may be desirable to provide a wellbore tool for sealing the wellbore to prevent fluid within the wellbore from flowing into productive formations when a wash tool or fracturing tool is being removed from the wellbore to replace deteriorated seal cups. If more than one productive formation is in fluid communication with the wellbore, it may be desirable to seal the wellbore to prevent cross-flow between productive formations. It may also be desirable to provide a wellbore tool for sealing the wellbore to prevent fluid flow from before the completion of well treatment operations, until after production tubing is run into the wellbore, and then later selectively allow fluid flow after the production tubing is set within the wellbore.
A wellbore tool for use to seal a wellbore and allow repeated retrieval of a wash tool or fracturing tool during well treatment operations requires a wellbore tool which is settable into sealing engagement within the wellbore, which is releasable from the workstring, which can be recoupled to the workstring for release from sealing engagement, and which is resettable for setting again into sealing engagement within the wellbore. Further, a wellbore tool for use to selectively prevent fluid flow within the wellbore from before the completion of well treatment operations, until after production tubing is run and set within a wellbore, requires a wellbore tool for running into the wellbore on a workstring, and then later either retrieved through production tubing or reset at another depth within the wellbore.
2(b). Description of the Prior Art
Hydraulically actuated wellbore tools, such as inflatable packers and inflatable bridge plugs, have been used for sealingly engaging wellbore surfaces to prevent fluid flow within wellbores. Some hydraulically actuated packers and bridge plugs are settable into sealing engagement within the wellbore, releasable from sealing engagement, and then resettable back into sealing engagement.
Other hydraulically actuated packers may be lowered within a wellbore on a workstring such as, for example, a coiled tubing string or a threaded tubing string, hydraulically urged into setting engagement, and then released from the workstring. Some of these packers may be recoupled to the workstring for release from setting engagement and retrieval from the wellbore.
Still other hydraulically actuated wellbore tools are inflatable packers which are run as part of a casing string for use in sealing an annulus between the casing string and a wellbore surface, such as the surface a borehole drilled through earth formations. These inflatable packers may be used as external casing packers for sealing against flow of formation fluid between different formation intervals about the wellbore. These inflatable, external casing packers are sometimes inflated by a straddle packer tool secured to a coiled tubing string which is lowered within the external casing packer for passing pressurized fluid to inflate the external casing packer into sealing engagement with the wellbore surface. Often these inflatable, external casing packers are cemented in place with the casing string to become permanently set within the wellbore.
However, none of the above hydraulically actuated wellbore tools are settable into sealing engagement within a wellbore, releasable from the workstring to allow retrieval of the workstring and a wash tool or fracturing tool during well treatment operations, resecurable to the workstring for release from setting engagement, and resettable into sealing engagement within the wellbore to allow further release from the workstring after being resecured to the workstring and released from setting engagement on a single trip into the wellbore.